The transmission, routing and dissemination of information has occurred over computer networks for many years via standard electronic communication lines. These communication lines are effective, but place limits on the amount of information being transmitted and the speed of the transmission. With the advent of light-wave technology, a large amount of information is capable of being transmitted, routed and disseminated across great distances at a high transmission rate over fiber optic communication lines.
When information is transmitted over fiber optic communication lines, impairments of the pulse of light carrying the information can occur, including pulse broadening (dispersion) and attenuation (energy loss). In-line amplifiers spaced throughout the fiber optic communication system boosts the power of each channel of the optical signal to assist in the compensation of the energy lost during transmission. The in-line amplifiers boost each channel of the optical signal with the same amount of power. However, as different wave lengths of light are used over the different channels of the fiber optic communication system, the amount of energy lost per channel is not consistent. As the in-line amplifier boosts the energy across all channels of the optical signal transmitted over the fiber optic communication system, the power gain of any specific channel may fail to meet or exceed the desired power gain. Further, energy loss caused by polarization dependent loss (PDL) lead to further nonuniform power gain over the multiple channels of the optical signal transmitted over the fiber optic communication system.
As the optical signal is transmitted across the fiber optic communication system, the gain differences on a channel-by-channel basis accumulate. These gain differences can cause distortions of the optical signal shape and therefore lead to performance degradation. Current systems allow for the optical signals' power deviations to accumulate before they are compensated by the gain equalizer after analysis by the optical spectrum analyzer (“OSA”). Inherent in these systems is a process which allows a large amount of gain differences to accumulate prior to equalization. Prior to the gain equalization of the channels of the optical signal, the optical signal performance beings to degrade and thus the overall performance of the fiber optic communications system is degraded.
To compensate for gain differences in the multiple channels of the optical signal, gain equalizers are provided, spaced periodically, throughout the fiber optic communication lines (FIG. 1). the gain equalizers equalize the power at the in-line amplifiers on a channel-by-channel basis throughout the optical signal. To determine the amount of gain on a channel-b-channel basis, an optical spectrum analyzer is co-located with the gain equalizer. The Optical measures the power level associated with each channel of the optical signal and compares this power level with the desired power level for each channel and provides this information to the gain equalizer which is co-located with the Optical spectrum analyzer at an in-line amplifier within the fiber optic communication system. The gain equalizer then equalizes the power of each channel based upon the analysis performed by the Optical spectrum analyzer at this in-line amplifier location. As can be seen in FIG. 2, the gain equalizer zeroes out the gain difference throughout the channels at the point in the fiber optic communication system where the gain equalizer and Optical spectrum analyzer are located. Therefore, any advancement in the ability to lower the amount of gain difference accumulated during the transmission of information over a fiber optic communication system would be advantageous.